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Message-ID: <20250912101145.465708-12-wangjinchao600@gmail.com>
Date: Fri, 12 Sep 2025 18:11:21 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Mike Rapoport <rppt@...nel.org>,
Alexander Potapenko <glider@...gle.com>,
Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>,
Valentin Schneider <vschneid@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
David Hildenbrand <david@...hat.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
Kees Cook <kees@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Sami Tolvanen <samitolvanen@...gle.com>,
Miguel Ojeda <ojeda@...nel.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Rong Xu <xur@...gle.com>,
Naveen N Rao <naveen@...nel.org>,
David Kaplan <david.kaplan@....com>,
Andrii Nakryiko <andrii@...nel.org>,
Jinjie Ruan <ruanjinjie@...wei.com>,
Nam Cao <namcao@...utronix.de>,
workflows@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
linux-mm@...ck.org,
llvm@...ts.linux.dev,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
kasan-dev@...glegroups.com,
"David S. Miller" <davem@...emloft.net>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
linux-trace-kernel@...r.kernel.org
Cc: Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v4 11/21] mm/ksw: add probe management helpers
Provide ksw_stack_init() and ksw_stack_exit() to manage entry and
exit probes for the target function from ksw_get_config().
The entry/exit probe handlers use atomic ksw_stack_pid to ensure a
singleton watch and current->kstackwatch_ctx.depth to track
recursion depth. A watch is set up only when depth reaches the
configured value.
Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
mm/kstackwatch/kstackwatch.h | 4 ++
mm/kstackwatch/stack.c | 113 +++++++++++++++++++++++++++++++++++
2 files changed, 117 insertions(+)
diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h
index 0786fa961011..5ea2db76cdfb 100644
--- a/mm/kstackwatch/kstackwatch.h
+++ b/mm/kstackwatch/kstackwatch.h
@@ -38,6 +38,10 @@ struct ksw_config {
// singleton, only modified in kernel.c
const struct ksw_config *ksw_get_config(void);
+/* stack management */
+int ksw_stack_init(void);
+void ksw_stack_exit(void);
+
/* watch management */
int ksw_watch_init(void);
void ksw_watch_exit(void);
diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c
index cec594032515..ac52a9f81486 100644
--- a/mm/kstackwatch/stack.c
+++ b/mm/kstackwatch/stack.c
@@ -1 +1,114 @@
// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/atomic.h>
+#include <linux/fprobe.h>
+#include <linux/kprobes.h>
+#include <linux/kstackwatch_types.h>
+#include <linux/printk.h>
+
+#include "kstackwatch.h"
+
+static struct kprobe entry_probe;
+static struct fprobe exit_probe;
+#define INVALID_PID -1
+static atomic_t ksw_stack_pid = ATOMIC_INIT(INVALID_PID);
+
+static int ksw_stack_prepare_watch(struct pt_regs *regs,
+ const struct ksw_config *config,
+ ulong *watch_addr, u16 *watch_len)
+{
+ /* implement logic will be added in following patches */
+ *watch_addr = 0;
+ *watch_len = 0;
+ return 0;
+}
+
+static void ksw_stack_entry_handler(struct kprobe *p, struct pt_regs *regs,
+ unsigned long flags)
+{
+ struct kstackwatch_ctx *ctx = ¤t->kstackwatch_ctx;
+ ulong watch_addr;
+ u16 watch_len;
+ int ret;
+
+ if (ctx->depth++ != ksw_get_config()->depth)
+ return;
+
+ if (atomic_cmpxchg(&ksw_stack_pid, INVALID_PID, current->pid) !=
+ INVALID_PID)
+ return;
+
+ ret = ksw_stack_prepare_watch(regs, ksw_get_config(), &watch_addr,
+ &watch_len);
+ if (ret) {
+ atomic_set(&ksw_stack_pid, INVALID_PID);
+ pr_err("failed to prepare watch target: %d\n", ret);
+ return;
+ }
+
+ ret = ksw_watch_on(watch_addr, watch_len);
+ if (ret) {
+ atomic_set(&ksw_stack_pid, INVALID_PID);
+ pr_err("failed to watch on depth:%d addr:0x%lx len:%u %d\n",
+ ksw_get_config()->depth, watch_addr, watch_len, ret);
+ return;
+ }
+
+ ctx->watch_addr = watch_addr;
+ ctx->watch_len = watch_len;
+ ctx->watch_on = true;
+}
+
+static void ksw_stack_exit_handler(struct fprobe *fp, unsigned long ip,
+ unsigned long ret_ip,
+ struct ftrace_regs *regs, void *data)
+{
+ struct kstackwatch_ctx *ctx = ¤t->kstackwatch_ctx;
+
+ if (--ctx->depth != ksw_get_config()->depth)
+ return;
+
+ if (atomic_read(&ksw_stack_pid) != current->pid)
+ return;
+ WARN_ON_ONCE(!ctx->watch_on);
+ WARN_ON_ONCE(ksw_watch_off(ctx->watch_addr, ctx->watch_len));
+ ctx->watch_on = false;
+
+ atomic_set(&ksw_stack_pid, INVALID_PID);
+}
+
+int ksw_stack_init(void)
+{
+ int ret;
+ char *symbuf = NULL;
+
+ memset(&entry_probe, 0, sizeof(entry_probe));
+ entry_probe.symbol_name = ksw_get_config()->function;
+ entry_probe.offset = ksw_get_config()->ip_offset;
+ entry_probe.post_handler = ksw_stack_entry_handler;
+ ret = register_kprobe(&entry_probe);
+ if (ret) {
+ pr_err("Failed to register kprobe ret %d\n", ret);
+ return ret;
+ }
+
+ memset(&exit_probe, 0, sizeof(exit_probe));
+ exit_probe.exit_handler = ksw_stack_exit_handler;
+ symbuf = (char *)ksw_get_config()->function;
+
+ ret = register_fprobe_syms(&exit_probe, (const char **)&symbuf, 1);
+ if (ret < 0) {
+ pr_err("register_fprobe_syms fail %d\n", ret);
+ unregister_kprobe(&entry_probe);
+ return ret;
+ }
+
+ return 0;
+}
+
+void ksw_stack_exit(void)
+{
+ unregister_fprobe(&exit_probe);
+ unregister_kprobe(&entry_probe);
+}
--
2.43.0
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